"Witsi Witsi" seems to be the most popular version of the name, but there are variations ranging from "Huitzi Huitzi" to "Gusi Gusi." Otherswise, the lyrics are pretty much identical to the English version of "The Itsy-Bitsy Spider," as is the melody. Any suspicion that this might have been a local variation or the creation of a particular teacher evaporated when one of the student's friends arrived and recognized the song. The friend was from Ecuador. (For those without maps handy, Ecuador and Bolivia aren't exactly neighbors.)
I haven't drawn any special insights from this. I just think it's an interesting example of cultural transmission.